During the coming year we propose to continue to develop a method of long-term stimulation of the phrenic nerve specifically for the treatment of chronic ventilatory insufficiency. Patient studies will include monitoring the electronic apparatus and monitoring the stimulation of the nerves by studies of pulmonary function, nerve conduction, and diaphragm function. Of particular interest are those patients who exhibit upper airway obstruction combined with central alveolar hypoventilation. Stimulation parameters will be varied first in the experimental animal and then in patients to diminish as much as possible the current delivered to the phrenic nerve and still provide adequate ventilation. Such variations are 1) current level, 2) wave form, 3) pulse interval, 4) respiratory rate, and 5) elctrode design. Other studies will be the completion of a prototpye totally implantable diaphragm pacemaker unit for patients.